The Large Magellanic Cloud: A Power Spectral Analysis of Spitzer Images

Abstract

We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud.The power spectra of the FIR emission show two different power laws.At larger scales (kpc) the slope is ~ −1.6, while at smaller ones (tens to few hundreds of parsecs) the slope is steeper, with avalue ~ −2.9.The break occurs at a scale ~ 100 − 200 pc. We interpret this break as the scale height of the dust disk of the LMC. We perform high-resolution simulations with and without stellar feedback.Our AMR hydrodynamic simulations of model galaxies using the LMC mass and rotation curve confirm that they have similar two-component power laws for projected density – and that the break does indeed occur at the disk thickness. Power spectral analysis of velocities betrays a single power law for in-plane components.The vertical component of the velocity shows a flat behavior for large structures and a power law similar to the in-plane velocities at small scales. The motions are highly anisotropic at large scales,with in-plane velocities being much more important than vertical ones.In contrast, at small scales, the motions become more isotropic.